# What is the difference between types of propeller? [closed]

I have been noticing almost every Multirotor vehicle uses a single thin double-bladed propellor on each axis. And yet clearly, there are some that do not fit the norm.

Can someone explain what the effect of each of these changes would do to a normal quadrocopter?

4) Making the angle of each blade steeper.

5) Replacing propellors with Contra-rotating propellers

6) Spinning Propellors faster

• Welcome to Aviation.SE. This seems to be quite a lot of points for a single question, please consider splitting these points in more than one question. – Federico Jul 2 '15 at 6:53
• Good reading about quadcopter desing: Build A Quadcopter From Scratch and for motors: How to choose Motor and Propeller for Quadcopter and Multicopter. – mins Jul 2 '15 at 10:11
• As for splitting this into multiple questions I'm not sure how exactly I would do that. I guess in general I was just asking how propellor design effects a quad, but that is just as broad. – iNeedToMakeBetterQuestions Jul 4 '15 at 10:59

There should be two parameters you should know about:

1. Blade loading: The amount of force per unit of area a blade is creating. Like with a wing, you can formulate a lift coefficient, a dimensionless number which removes the influence of size, air density and speed. Ideally, this number should be between 0.5 and 0.7, so the propeller makes best use of its blade area.
2. Advance ratio, which is the ratio between the circumference of the propeller disc and the height it would screw itself up into the air in one rotation. Increasing the blade angle would directly increase this advance ratio, for example.

Now you should be able to guess the answers to your questions: